(683a) Entropy-Driven, Two-Step Crystallization of Colloidal Clathrate Crystal

Non-classical crystallization, such as two-step crystallization, is the primary mechanism of solidification for many substances. Despite its importance, aspects of the system responsible for determining the crystallization mechanism are generally poorly understood. Identifying idealized model systems that exhibit non-classical crystallization is therefore desirable. Here, we report two-step crystallization in a three-dimensional system of hard shapes. Unlike previous reports of two-step nucleation and growth, in our system it is driven by entropy alone. Monte Carlo simulations reveal that crystallization is preceded by the appearance of a dense amorphous phase.The thermodynamics of crystallization is investigated by determination of the equation of state and via free energy calculations.